Basic Probability Rules

Felicity attends Modesto JC in Modesto, CA. The probability that Felicity enrolls in a math class is 0.2 and the probability that she enrolls in a speech class is 0.65. The probability that she enrolls in a math class GIVEN that she enrolls in speech class is 0.25. Let: M = math class, S = speech class, M|S = math given speech What is the probability that Felicity enrolls in math or speech classes? (write your answer to 4 decimal places)

All human blood can be typed as one of O, A, B, or AB, but the distribution of the types varies with race. Here is the distribution of blood types of black Americans. Suppose we choose one black American at random. What is the probability that the chose person has type AB blood? Remember: there is a larger version of the charts on my website!

• 0.04

• 0.09

• 0.16

• 0.218

Canada has two official languages: English and French. Choose a Canadian at random and ask "What is your mother tongue?" Here is the distribution of responses, combining many separate languages from the broad Asia/Pacific region. What is the probability that this person's mother tongue would be classified as "other"? Remember: there is a larger version of the charts on my website!

• 0.04

• 0.09

• 0.16

• 0.218

In government data, a household consists of all occupants of a dwelling unit. Choose an American household at random and count the number of people it contains. Here is the assignment of probabilities for the outcome. (The probability of finding 3 people in a household is the same as the probability of finding 4 people.) What probability should replace "?" in the table? Remember: there is a larger version of the charts on my website!

• 0.04

• 0.09

• 0.32

• 0.16

The National Household Travel Survey gathers data on the time of day when people begin a trip in their car or other vehicle. Choose a trip at random and record the time at which the trip started. Here is the assignment of probabilities for the outcome. What probability should replace the "?" in the table? Remember: there is a larger version of the charts on my website!

• 0.964

• 0.379

• 0.752

• 0.218

If you are picking a card randomly from a deck of cards, the events of picking an ace and picking a ‘3’ are mutually exclusive.

• True

• False

When rolling a single die, the events of rolling an even number and rolling a ‘5’ are mutually exclusive.

• True

• False

If a spinner is numbered 1 – 8, when you spin it the events of spinning an even number and a number less than 4 are mutually exclusive.

• True

• False

A bag contains 9 green marbles, 5 yellow marbles and 6 red marbles.  You choose one marble.   What is the probability of selecting a green or red marble?

• 8/15

• 6/11

• 3/4

• 2/3

What are mutually exclusive events?

• Events that can happen at the same time

• Events that cannot happen at the same time

• Events that add up to 100%